I think this book's greatest weakness is that it doesn't have a clear handle on its intended genre. It's made for a horror game but is largely about rank and office politics. You might think that as the sorcerers of the vampire world, the Tremere could support a more urban fantasy brand of horror, but there was little of that in evidence. By wordcount, it was mostly about navigating an expectation towards obedience, and the rewards of breaking the rules without getting caught. There's a bit of a creep factor, because vampires, but this is by far the most bloodless (both a literal statement and a pun) of the vampire clanbooks so far.
But it's also among the most useful, as both a player and a GM resources. It does an effective job at communicating a culture. When you're playing as a Tremere, you're going to find yourself asking "who's ass do I have to kiss and/or who do I have to kill to get a promotion around here" and this book will help you to quickly identify them. It's also the only clanbook I've read which spares some space to explore what a one-clan-only game would have to look like, and frankly it's bizarre to me that this wasn't standard practice (it's funny, it's only been a couple of years since I read the mage traditionbooks, and I seem to recall them occasionally doing stuff like that, but aside from Traditionbook: Dreamspeakers, concrete examples elude me).
The history section was . . . fine. I appreciated that it dealt with specific events, happening recently enough in history to have some level of documentation, but I have to confess that I'm now seeing the upside of just picking a random historical figure that seems like they'd fit the clan's vibe and then giving them a ridiculous World of Darkness alt-history. Without at least one or two of those guys to make me go wtf, you wind up with precisely one line in my notebook, "narrator doesn't know what happened to medieval mages."
Which I suppose brings us to the crux of the issue. Clanbook: Tremere doesn't do horror very well, but it also doesn't do much with the clan's fantasy elements. I remember the early 2000s as a period when White Wolf was especially down on cross-overs, and perhaps the book fell victim to a new policy (I can only assume that this is the reason the events of Blood Treachery get no mention here, despite Jess Heinig being the developer of that earlier book). Certainly, they're the only one of the clans whose "external relations" section claims that mages are entirely extinct.
So, what we've got is a clan where a lot of its identity is rooted in this Order of Heremes backstory that goes all the way back to when White Wolf controlled the rights to Ars Magica, but very little of that backstory is actually used. Thus, instead of having an identity as wizards whose hubris led them to believe they could conquer the Kindred (there's some of that here, but it's dilute), they're kind of just left with the stuff that's unique to their Vampire: the Masquerade context - they're the vampires who are really into hierarchy and sometimes act like they have a stick up their ass.
I think, to be really effective, what a Tremere clanbook needed was more of a sense of transgression and outrage. The Tremere have so many enemies because they usurped the powers of better, more worthy vampires. Funnily enough, their ideal energy is probably pretty close to Samuel Haight.
Wait . . . do you think that maybe the reason they got such a workhorse of a book is because this is right around the time White Wolf turned Samuel Haight into an ashtray?
Ukss Contribution: You know, for a book about undead sorcerers, blasphemously twisting their unholy curse into a source of occult power, I've actually got surprisingly little inspiration for an Ukss entry. The part where some vampires will breastfeed their homunculi was kind of creepy, I guess, but is that really a thing?
I think this time, I have to go with something from the art, rather than the text.
What is even going on here? There is absolutely nothing in the text to give this even the slightest bit of context. It belongs in a better, more bizarre book.